1. Field of the Invention
The present invention generally relates to semiconductor devices, and more particularly, to a mechanism for protecting a semiconductor device from electrical overstress damage by electrically grounding the device during processes where an electrical charge can build up on the device.
2. Background Information
Semiconductor devices such as integrated circuit (“IC”) devices have become key components of many consumer and commercial electronic products, often replacing discrete components and enhancing functionality. The semiconductor processing technologies that produce these devices have advanced to the point where complete systems, including memories, can be reduced to a single IC device.
Producing an IC device includes a number of individual processes. These processes include an assembly process where a wafer of semiconductor material is cut into a plurality of individual wafer dies. Each die is then assembled into a package by applying to each die an exterior coating typically comprised of an epoxy or ceramic material. A packaged die is often referred to as a packaged semiconductor device, or “chip.”
Once packaged, an individual die may be placed through a variety of functional tests, either in the lab or in the field. Such tests may reveal that the packaged die is operating properly, or alternatively, may reveal that the packaged die is defective. In either case, it is often useful to determine why an individual packaged die operates in a particular manner.
Reactive ion etching (“RIE”), for example, is one commonly used technique to examine the internal structure of an individual die, and thereby determine why the die operates in a particular manner. In general, RIE involves using an electrically charged plasma to activate reactive ions which anisotropically (directionally) etch the die with varying degrees of selectivity. Accordingly, by using RIE, horizontal and/or vertical layers of a die may be selectively removed and the internal structure of the die may be examined. RIE is often used for delayering a die since it results in precise and repeatable etch rates, has good selectivity and can produce anisotropic etches which do not undercut metal layers on the die. Devices for performing RIE are commercially-available from companies, such as Nextral.
When performing an RIE process, a packaged die is typically placed within a shuttle device that exposes a portion of the packaged die to an RIE chamber where the reactive ions are present. Moreover, the shuttle device electrically insulates other portions of the packaged die from the RIE chamber to prevent their exposure to the reactive ions. For example, the shuttle device may insulate electrically conductive terminals (e.g., pins, solder balls, etc.) of the packaged die from the RIE chamber.
Despite the insulating function of the shuttle device, an electrical charge may accumulate on the packaged die during the RIE process. This electrical charge may cause electrical overstress damage to the packaged die, and thus destroy its ability to function in an intended manner.
Accordingly, there is a need for a mechanism that protects a packaged die from such electrical overstress damage during processes, such as an RIE process, where an electrical charge can build up on the device. The present invention addresses these and other issues.